Generally, there are four categories of golf clubs: (1) long distance clubs, such as woods or drivers, and low number irons; (2) intermediate range irons; (3) short range irons; and (4) putters. The properties of composite materials can be optimized for use in golf club heads by the judicious selection of the components of the composite materials, thus providing advantages over traditional materials, such as: wood, forged carbon steels, investment cast stainless steels, copper based alloys, nickel based alloys, cobalt based alloys, and titanium based alloys.
Over many years numerous attempts have been made to optimize the performance of golf clubs. Focus for optimizing performance has been made upon shafts, grips, heads, etc. However, much improvement is still possible in many of those areas as various new technologies are discovered. For example, some efforts have been directed toward proper selection and/or combination of materials for use as golf club heads. However, while some success has been achieved, the potential for further improvement still exists.
An attempt to utilize composite materials in golf club heads is disclosed in U.S. Pat. No. 4,883,275, issued to David D. Boone. This patent teaches that iron golf club heads comprised of an outlying or peripheral structure of a light-weight non-metallic composite material and a metallic insert forming the face, sole, and back weight produces an improved iron golf club head. The improved iron golf club head has a desirable weight distribution, provides for improved utilization of the mass of the head, and allows for improved control of the location of the center of gravity which tends to reduce the likelihood of error in shots. The disadvantage of the Boone Patent is that the outlying non-metallic member is made from an epoxy impregnated graphite. The epoxy of these polymer matrix composites is susceptible to moisture absorption which would distort the outlying member of the club head in humid climates, thus, obviating any of the advantages from use of such materials.
Another attempt to utilize composite materials is disclosed in U.S. Pat. No. 4,768,787, issued to Chester S. Shira, and entitled "Golf Club Including High Friction Striking Surface". This patent discloses a high-friction ball striking surface on the head of a metal iron which permits long term use without deterioration of the friction causing elements in the surface. Specifically, the ball striking surface of the iron head has hard, sharp featured particulates protruding therefrom, which particulates would increase the friction between the ball striking surface and the ball so as to impart a desired backspin on the ball. Another feature of the Shira invention is that the particles are supported in a matrix of a softer metallic material which wears away through use, and continues to expose hard, sharp featured particles embedded therein. One disadvantage of such a surface is that the soft matrix metal placed onto the substrate to embed these protruding sharp featured particles is different from the substrate material of the face; therefore, a difference in properties of the metallic substrate and the embedding matrix might result in spalling of the gripping surface.
U.S. Pat. No. 4,687,205, issued to Tominaga, et al., and entitled "Iron Type Golf Club Head" teaches a method of making an iron type golf club head comprising a composite material of light metal or synthetic resin containing silicon carbide whiskers which consist of 2-80% by volume of the golf club head and which occupy 20% or more by volume of the body of the club head. The club head can be 10-60% lighter than the club head made entirely of steel with the same configuration and size, while the moment of inertia is approximately the same. Weight metal inserts having a specific gravity greater than steel can be embedded in the club head.